1. Technical Field
This invention relates in general to telecommunications and, more particularly, to telecommunications using optical fibers.
2. Description of the Related Art
Cross-connect switches are used to provide switching between long haul and other communication lines to allow service providers easy reconfiguration of connections through their network. Traditionally, cross-connect switches operated on the electrical domain, even if the cross-connect switch was handling optical (e.g. SONET) traffic.
Today, communications technology is providing higher data rates carried in optical channels. Accordingly, a new optical layer is evolving to manage the optical channels. In order to provide cross-connect capabilities, as well as other features that have been available at other network layers, optical cross-connect switches are under development. These cross-connect switches will provide signal routing in the optical domain without conversion to electrical signals in order to provide transparency to the signal's timing and to eliminate the cost of converting to and handling very high-speed electrical signals.
One important function of all cross-connect switches involves inspecting the data stream of a channel to ensure that there are no errors in the cross-connected signals due to misconnections between ports. Normally, in an electrical domain, a few bytes of data that uniquely identifies the origination port are added into reserved data fields of the communications data stream by the originating I/O port of the cross-connect switch. These identification bytes are checked at the destination I/O port to ensure that the connection through the cross-connect switch was properly implemented.
Once in the optical domain, however, adding data to the received communications data stream would require a translation of the optical data stream into an electrical data stream to add the port identification information, with a second translation of the electrical data stream into an optical data stream. Converting signals to an electrical format in order to add the identification bits is undesirable because of the expense of the conversion circuitry.
Therefore, a need has arisen for an inexpensive method of ensuring the validity of connections through an optical matrix without conversion of the communications data stream into an electrical data stream.